Method and apparatus for the manufacture of tubes



F. E. FIEGER Oct. 30, 1934.

METHOD AND APPARATUS FOR THE MANUFACTURE OF TUBES Filed March 10. 1931 2Sheets-Sheet l FMEF QZZZSL AM Oct. 30, 1934. FIEGER 1,978,422

METHOD AND APPARATUS FOR THE MANUFACTURE OF TUBES Filed March 10. 1933.2 Sheets-Sheet 2 ill;

INVENTOR PM E'FQ'KI Patented a. 30, 1934 UNITED STATES PATENT OFFICErm'rnon AND APPARATUS Foa run MANUFACTURE or runes Application March 10,1931, Serial No. 521,486

paratus for the manufacture of tubes, the word "tubes being used as aword of broad definition and not limitation, and being intended todesignate tubular products generally regardless of their mercantileclassification.

There is a great demand for seamless steel tubes, which demand hasheretofore been supplied by a process of manufacture involving piercingof a solid billet. followed by rolling on an automatic return mill, orplug mill as it is sometimes termed. The piercing is effected in a millof the Mannesmann or Stiefel type wherein a pair of rolls simultaneouslyrotates and transversely compresses the steel billet while feeding itforward over a piercing point. In order to get satisfactory yields it isnecessary to employ a high grade'of steel, as otherwise there will betoo great a loss in the piercing mill. The quality of go the steel tobeused is determined, not by the requirements of the final product, but bythe necessities of manufacture. The piercing opera-.

tion requires careful and constant supervision and the expenditure ofhigh power. Difficulty is frequently had in obtaining concentricity.

I provide for forming a tube blank by the push-bench process andsupplying such blank to an automatic return mill for further elongationand reduction of wall thickness. According to the push-bench process ofmanufacture, a heated billet of relatively short length is placed in apress and punched for a major portion of its length so as to form ahollow body closed at one end. This body is placed over the end ofa-mandrel and pushed through a ring bench carrying dies of successivelydecreasing diameter. The dies reduce the diameter of the blank andelongateit over the mandrel. The common practice is to form the tubecompletely on the push bench except for small sizes where, as in thecase of the piercing and plug mill method, resort is had to a reducingmill for elongating and decreasing the diameter of a formed tube.

I have found, however, that material advantages may be derived fromcombining the push bench process with the automatic return'mill, andthat high quality tubes may be thereby produced at relatively low cost.The push bench permits of using a quality of'steel which, while 5entirely satisfactory in the finished product,

need not be so carefully supervised in its manufacture as steel intendedfor the piercing process. Material economies are thereby effected at theoutset. The trend of consumers is toward long length tubes, and wherethe tube is produced 9 Claims. (01. za-sa) This invention relates to amethod and apsolely by the push-bench process it is necessary to employa mandrel longer than the longest length of finished tube desired(barring those sizes which are produced-in the reducing mill). Theamount of reduction per die in the push bench is limited, for the forceexerted by the die must not be so great that the endof the mandrel willpunch its way through the closed end of the blank. This tendency of themandrel also limits the number of dies which may be active at any onetime. For example, in the earlier and heavier reductions it may beconsidered advisable to have the blank in only two dies at any one time.Consequently, if the tube is to be reduced to final size in the pushbench it requires an installation of very great length, necessitating alarge captial investment. Moreover, this extreme length renders morediflicult the problem of maintaining the tube truly concentric, sincethe mandrel derives its entire support from the connection to the pushbar at the rear end of the mandrel and, radially, only through the hotmetal which is being worked.

If, on the contrary, the push bench is relied on only to form a tubeblank of relatively heavy wall thickness and limited length, the totallength of the push bench may be greatly reduced and the shorter mandrelbars will be stifier, resulting in more concentric tubes. There will beless heat loss and a faster cycle of operations is possible. Materialeconomies in power may also be effected.

In the accompanying drawings illustrating a present preferred embodimentof my invention,

Figure 1 is a plan view of an installation for the manufactureoftubes,'and

Figure 2 is a view to enlarged scale of a portion of Figure 1.

Figure 1 illustrates a furnace 2 having a pusher 3 whereby squarebillets B are fed through the furnace and brought up tov heat. Sidedoors 4 are provided so that after the billets reach the delivery end ofthe furnace they may be engaged by tongs and turned over so as toseparate the leading billets in the train from one another, therebyequalizing the heat. The heated billets are discharged through doors -5to transfer cars 6 leading to the press '7. The press has a cylindricaldie 8 which receives the square billet, and a circular punch 9 is forcedinto it so as to produce a bottle or tube blank. This blank is ejectedfrom the die 8 and carried by a swinging arm 10 to a position indicatedat C on the push bench 11. A mandrel 12 is inserted in the throttle andthe mandrel is then pushed forward to re- Q AQQ the tube. It issupported at its rear end on 1 a push bar 13 extending forwardly from arack 14 driven by a motor 15. When the motor is actuated to drive themandrel to the right, as viewed in Figure 1, the bottle is pushedthrough a series of dies 16 successively decreasing in diameter, so thatwhen the mandrel has been pushed completely through the dies, a tubeblank T has been formed thereon from the bottle. The mandrel isdisconnected from the push bar 13 and lies on a roll table 17. It is fedforward through a reeler 18 which loosens the tube on the mandrel anddelivers it to table rollers 19. The tube and mandrel are then fed overskids 20 to table rollers 21 which hold the mandrel in alinement with astripping die 22. The rear end of the mandrel is fed through thestripping die by actuating the table rollers 21. This end is grasped bya tongs 23 connected to a chain 24. The chain is pulled to the left by amotor 25, thus drawing the mandrel out of the tube blank. The tube blankis then carried away from the stripping die 22 by means of the tablerollers 21 and kicked off onto skids 26 over which it rolls until it isreceived by table rollers 27.

The stripped mandrel, after being released by the stripping tongs 23,may be carried by table rollers 28 to skids 29 from which it is fed backto the push bench 11, or it may be carried over transfer skids 30 totable rollers 31 and thence back to the skids 29 by reason of areheating furnace 32 which equalizes the temperature of the mandrel.This feature is more fully described and claimed in a copendingapplication-0f Carl W. Littler, Serial No. 513,307, filed February 4,1931. After the tubereaches the table rollers 27 it is fed forward sothat its ends may be cut off by a hot saw 33. After the ends have beenout 01f the tube blank is lying on table rollers 34 from which kick-offs35 transfer it to rollers 36. A pusher 37 then feeds the tube blank to areheating furnace 38 from which reheated tubes are delivered by. reasonof a pusher 39 (see Figure 1) to rollers 40. If desired, the tubes maybe fed directly from the rollers 36 to the rollers 40 over skids 41.

A kick-off 42 transfers the tube blank to the trough 43 of an automaticreturn mill indicated generally by the reference character 44. This millcomprises driven rolls 45 supplied with power from a motor 46 (seeFigure 1), a pusher 46a for moving the tube blank into the grip of therolls, a bar 4'7 extending from a back-stop 48 and adapted to supportplugs P over which the tube is rolled, and return rolls 49. Inoperation, the rolls 45 feed the tube blank, once it has been moved intotheir grip, and roll it over the plug P, reducing its wall thickness andelongating the blank. When the tube has been fed all the way through therolls 45 are separated and the return rolls are automatically renderedeffective for feeding the tube back to the trough 43. The upper returnroll 49 is fixed in position, while the lower roll is automaticallymoved upwardly so'as to frictionally engage the tube after the reducingrolls 45 have been separated. The return rolls are driven by a motor 50.The construction and operation of the plug mill are well known andrequire no extended description. A workman puts a fresh plug on the endof the bar 47 after each reducing pass and the tube blank is turnedthrough 90. Several passes are given and the tube is thereby reduced andelongated. When the plug rolling has been completed the tube is liftedby kick-offs 51 onto skids 52 over which it travels to a roll table 53.If desired it may be lifted from the roll table 53 by kick-offs 54 toskids 55 leading to a roll table 56. The roll tables 53 and 56 are inalinement with reelers 57 which roll the tubes helically over plugs heldby freely rotating mandrel bars 58. The mandrel bars 58 are held againstendwise movement during the reeling of the tube, but after the tube hascleared the reeler the mandrel bar is withdrawn by a mechanism indicatedgenerally at 59. The rolling operation serves to reduce any inaccuraciesof wall thickness and to smooth and round the tube. From the reelers thetubes pass to a roll table 60 and thence to a sizing mill 61 wherein thetube is brought down to the precise outside diameter required. From thesizing mill the tubes pass to a cooling rack 62.

I have illustrated and described a present preferred embodiment of myinvention but it will be understood that this is by way of illustrationonly and that the invention may be otherwise embodied or practicedwithin the scope of the following claims.

I claim:

1. In the method of making tubes, the steps consisting in subjecting ahollow heated metal body to the action of successive reducing dies,thereby forming a tube blank, and elongating the blank and thinning itswall by rolling it over a plug while maintaining the plug stationary inthe direction of advance of the blank.

2. In the method of making tubes, the steps consisting in placing on theend of a mandrel a hollow heated metal body having one end closed, andsubjecting it'to the action of successive reducing dies, therebyelongating the metal body over the mandrel and forming a tube blank, andfurther elongating the blank and thinning its wall by rolling androtating it over a plug.

3. In the method of making tubes, the steps consisting in subjecting ahollow heated metal body to the action of successive reducing dies,thereby forming a tube blank, and elongating the blank and thinning itswall by a plurality of plug rollings.

4. In the method of making tubes, the steps consisting in placing on theend of a mandrel a hollow heated metal body having one end closed andsubjecting it to the action of successive reducing dies, therebyelongating the metal body over the mandrel and forming a tube blank,removing the blank from the mandrel, opening the closed end, and furtherelongating the blank by subjecting it to a plug rolling.

5. In the method of making tubes, the steps consisting in placing on theend of a mandrel a hollow heated metal body and subjecting it to theaction of successive reducing dies, thereby forming a tube blank,reheating the blank, and further elongating it and thinning its wall byrolling it over a plug.

6. In the method of making tubes, the steps consisting in placing on theend of a mandrel a hollow heated metal body and subjecting it to theaction of successive reducing dies, thereby forming a tube blank, andbefore the blank cools further elongating it and thirming its wall byrolling it over a plug while maintaining the plug stationary in thedirection of advance of the blank.

7. Apparatus for the manufacture of tubes comprising a push bench, amill of the type commonly known as a plug mill which comprises a plugpositioned substantially stationarily in the direction of advance ofblanks therethrough,

9. Apparatus for the manufacture of tubescomprising a push bench, a millof the type commonly known as a plug mill which comprises .a plugpositioned substantially stationarily in the direction of advance ofblanks therethrough for reducing blanks formed on the push bench, andmeans for heating such blanks.

FREDERICK E. FIEGER.

